Alanin‐Dehydrogenaseaktivität und Antibioticumbildung in Kulturen des <i>Streptomyces hygroscopicus</i> JA 6599

Abstract

Abstract In order to estimate the role of alanine dehydrogenase (EC 1.4.1.1) in the precursor supplying system of antibiotic A 6599 biosynthesis by S. hygroscopicus JA 6599 the activities of this enzyme were studied in mycelial extracts. Within the production phase of antibiotic A 6599 only slight differences in the enzyme activities of two strains producing different amounts of antibiotic were found. After the 2nd day of fermentation in complex medium cultures, however, a striking increase in alanine dehydrogenase activity was observed suggesting that variations of metabolism took place. This might be responsible in part for decay in antibiotic production due to deficiency of pyruvate as an intermediate of precursor formation. Evidence is given for enzyme induction by an excess of alanine or ammonia in the medium. The addition of the antibiotic A 6599 to producing cultures causes a suppression of mycelial growth and ammonia metabolization as well as repression of the phosphoenolpyruvate carboxylase (EC 4.1.1.31) but it doesn't prevent completely regulating de novo synthesis of enzymes as alanine dehydrogenase. The results point to the interference of the antibiotic A 6599 in the producing strains of this organism both with the metabolic regulation and precursor supply.